Climate-smart push–pull 1

Climate-smart push–pull:resilient, adaptable conservation agriculture for the future

icipeAfrican Insect Science for Food and Health

Mary Otuoma, a widow who lives with her daughter-in-law and two grandchildren in Bondo district, Kenya, farms a single acre. She is pictured in front of her climate-smart push–pull plots with sorghum (foreground) and maize (background). “I now have enough food,” says Mary, “and I have been able to buy a sheep. My poverty is alleviated.”

Developing adaptable, productive agricultural systems

that are resilient to the risks and shocks associated with

long-term climate variability is essential to maintaining

food production into the future. But resilience is not

enough. Climate-smart agricultural systems also need to

protect and enhance natural resources and ecosystem

services in ways that mitigate future climate change.

Push–pull is a conservation agriculture technology

developed for smallholder mixed farming systems. The

livelihoods of 80% of the population of sub-Saharan

Africa (SSA) depend on these systems. Push–pull farmers

establish perennial stands of two fodder crops, one

between the rows of their main cereal crop and the other

around the field. The natural chemicals produced by

these companion plants effectively control stemborers

(insect pests) and parasitic weeds in the genus Striga.

When farmers adopt push–pull, as more than 115,000

have done since 1998, they not only achieve a dramatic and

sustainable increase in cereal yields, they also benefit from

enhanced soil fertility and obtain year-round fodder crops. This

strengthens the foundations of their farming and livelihood

systems, making them both more productive and more resilient.

Although farmers have successfully used push–pull

since it was first extended in 1998, in recent years they

began reporting that the companion plants could not

always withstand the long seasonal dry spells that were

becoming more frequent. Through new research in 2011,

this led to the development of a ‘climate-smart’ push–pull,

which includes two new drought-tolerant companion plants.

Building on the already formidable pest management

and soil improvement characteristics of the technology,

climate-smart push–pull can be extended to dryer agro-

ecosystems and applied to a wider range of cereal crops.

2 Climate-smart push–pull

In Lambwe Valley, Mbita district, Kenya, this maize crop has failed due to a long dry spell, and the farmer has released his livestock into the field to graze the plants.

Africa’s persistent poverty…Africa faces particular problems in feeding its population

and it is the only continent in which per capita food

production has been declining over the past two

decades. In SSA, land degradation, pests and weeds

hamper the efficient production of cereals, particularly

maize, the main staple and cash crop. Low and declining

yields are affecting food security, nutrition and incomes,

trapping farmers in poverty and poor health. The

resource-constrained smallholder farmers living in the

arid and semi-arid regions who practice mixed crop–

livestock production are particularly badly affected.

In addition to widespread poverty, population pressure

on the land is high in many areas. In many parts of the

region, smallholdings commonly amount to just one

hectare or less. Soils are severely degraded and have low

organic matter as a result of continuous monocropping,

lack of investment in soil improvement and the removal

of crop residues for livestock fodder. Most fields are

heavily infested with parasitic striga weeds, while insect

pests – principally stemborers – devastate cereal crops,

commonly causing over half the potential harvest to be lost.

Many families remain trapped in a cycle of diminishing

yields and deepening poverty. Food insecurity is already

common, with a critical shortage of cereals in almost

70% of rural households. This is the backdrop to the

challenge of intensifying agriculture sustainably to meet

the extra demand for food from a growing population.

There is an urgent need for a significant and sustainable

increase in grain yields and animal production. In

particular, sustainability requires ecologically sound ways

of managing weeds and pests, and a strong focus on

maintaining and conserving soil, crop and water resources.

…and the compounding effects of climate changeClimate change is anticipated to have far-reaching effects

in Africa, threatening many of the advances made through

efforts to achieve the Sustainable Development Goals

by 2030. Ensuring the continuity and sustainability of

development in the context of climate change will be at the

centre of post-2015 international development agendas.

Studies to predict the effects of climate change

suggest that, by 2025, growing-season average

temperatures will be warmer than those of 1960–2002

for four years in ten for the majority of Africa’s maize-

growing areas. This is projected to reach nearly nine

years in ten by 2050, and nearly ten by 2075.

Climate models also suggest that rainfall will become

progressively more unpredictable, with a decline in yearly

totals and increasing incidence of floods and droughts.

These climate trends are likely to lead to worsening

land degradation and pest and weed pressure, with crop

failure occurring more often, exacerbating food insecurity.

To adapt to these adverse conditions, many resource-

constrained smallholder farmers will need to modify their

farming systems to incorporate cereal crops with greater

drought resistance, such as sorghum and millet, and to

replace cattle with small ruminants for dairy production.

Push–pull: a broad-based solutionPush–pull has already proven its success as a conservation

agriculture technology that simultaneously addresses

many of the constraints faced by smallholder farmers,

dealing effectively with pests and weeds, increasing

the productivity of crops and livestock, and supporting

several important agro-ecosystem functions.

The new climate-smart adaptation of the push–

pull technology has unrivalled potential to continue

to address these problems at the same time as

equipping farmers with the increased resilience and

adaptability they need to deal with the additional

problems associated with climate change.

What is climate-smart push–pull?Developed by icipe and its partners, push–pull is a novel

conservation agriculture technology designed to integrate

pest, weed and soil management in cereal-based farming

systems. It involves driving cereal stemborers away from the

crop by using a repellent intercrop plant, desmodium (the

‘push’), while at the same time attracting stemborers with a

border crop of native grass trap plants (the ‘pull’). Chemicals

released by the desmodium roots also result in very

effective control of the troublesome parasitic weed striga.

As well as controlling stemborers and striga, the push–

pull companion plants provide high-value animal fodder,

which farmers can sell or feed to stall-fed dairy cows and

other livestock. The companion plants also increase soil

fertility, prevent soil erosion and conserve soil moisture.

Climate-smart push–pull 3

How does push–pull work?

Conventional push–pull was developed in 1997 and introduced to farmers in 1998. It uses silverleaf desmodium (Desmodium uncinatum) and Napier grass (Pennisetum purpureum).

Climate-smart push–pull was developed in 2011 and introduced to farmers in 2012. It uses two drought-tolerant species: greenleaf desmodium (Desmodium intortum) and Brachiaria grass (Brachiaria cv mulato II).

See www.push-pull.net for more information.

The parasitic weed Striga hermonthica does not make its own nutrients, instead drawing its nourishment from the cereal roots.

Push–pull prevents stemborers attacking cereals by intercropping with a ‘push’ plant, such as desmodium, and planting around this intercrop a border of a stemborer-attractive ‘pull’ plant, such as Napier grass or Brachiaria grass.

In addition to repelling or pushing the stemborers away from the crop, desmodium suppresses the parasitic weed, striga. It stimulates germination of the striga seeds, then inhibits the growth of its roots, thereby preventing the striga attaching itself to the host plant.

On top of dealing with stemborer and striga, the leguminous desmodium intercrop fixes atmospheric nitrogen, adds organic matter to the soil, conserves soil moisture and enhances soil biodiversity, thereby improving soil health and fertility. Additionally, it provides ground cover and, together with the surrounding grass trap crop, protects the soil against erosion.

Stemborer larvae feed first on the leaves of the maize plant, before going on to bore into the stem.

The technology fits well with traditional African

mixed cropping systems. Based on locally available

plants, rather than expensive external inputs, it is

both appropriate and economical. By improving the

productivity of a wide range of crops and livestock,

it diversifies farmers’ income sources. Through being

equally accessible to female and male farmers, it

contributes positively to gender equity. Perhaps

most importantly, push–pull farmers commonly

report a doubling and tripling of their maize yields

and their food security is greatly increased.

Funding from the European Union has allowed

further research to adapt push–pull to predicted drier

and hotter conditions by identifying and incorporating

drought-tolerant trap and intercrop plants. This has

led to a new, climate-smart push–pull package being

extended to farmers, comprising an intercrop of greenleaf

desmodium and a border crop of Brachiaria grass. As

well as directly addressing soil fertility and productivity

constraints, climate-smart push–pull responds directly to

the rising uncertainties facing Africa’s rain-fed agriculture

due to the continent’s vulnerability to climate change.

The sorghum plot on the left is infested with the purple flowers of striga, while the climate-smart push–pull plot on the right is completely free from the weed.

The climate-smart push–pull demonstration plot at Mbita Point.

4 Climate-smart push–pull

Why climate-smart push–pull?The trap plants and intercrops used in conventional

push–pull were developed to suit the current average

rainfall (>800 mm per annum) and moderate temperatures

(15–30°C) of Western Kenya. The rising uncertainties of

rain-fed agriculture for farmers in this region and those

in warmer, drier agro-ecosystems led icipe scientists to

begin the search for new trap plants and intercrops.

Working with Rothamsted Research, UK and national

partners in Ethiopia, Kenya and Tanzania, icipe scientists

tested a total of 500 potential grasses, identifying 21 that

were suitable for controlling stemborers. They then worked

with farmers to select the trap plant of their choice.

The grass that farmers selected, Brachiaria, controls

stemborers effectively by supporting a parasitic wasp

which feeds on their larvae. Crucially, it can also

withstand periods of up to four months with no rainfall,

and temperatures in excess of 30°C. In addition,

the grass is extremely palatable to livestock.

At the same time, the team worked to identify new

species of desmodium. They needed species that

not only had the desirable characteristics of silverleaf

desmodium – controlling striga, emitting volatiles to repel

stemborers, fixing nitrogen, producing high biomass

and spreading on the ground – but were also drought

tolerant. Forty-three accessions of 17 species were

collected from arid regions across Africa, and greenleaf

desmodium was selected. In addition to its known ability

to control striga and stemborers, it fixes more atmospheric

nitrogen and produces more fodder than silverleaf .

Both Brachiaria and greenleaf desmodium seed

are commercially available, which meant that the new

climate-smart push–pull package could be rapidly

disseminated to farmers. Scientists have also identified

two native African desmodium species (D. ramosissimum

and D. repandum) that are even more drought tolerant

than greenleaf (D. intortum), but for which there is no

commercially available seed at present. Looking to

the future, icipe is building partnerships with farmers

and seed companies to address this constraint.

The icipe team and Rothamsted scientists are continuing

their work to more fully understand the chemistry behind

desmodium’s ability to suppress striga, by isolating and

purifying the active compounds in exudates from drought-

tolerant desmodium roots. Similarly, they are examining

the full mechanism of stemborer control in Brachiaria grass.

This will ensure the future sustainability of the climate-smart

push–pull technology and allow its wider adaptation.

Partnerships in implementationWhile push–pull is in many ways an elegantly simple

technology, it is based on a set of complex ecological

and chemical relationships between plants, insects

and soil. Scientists at icipe have found that push–

pull works best in practice when farmers understand

clearly how it works. This has made disseminating

push–pull a knowledge-intensive process, with a strong

emphasis placed on building farmers’ capacities.

District-based icipe field workers usually deliver

training by working with farmer groups established

for mutual support and self-help, but also often visit

individual farmers to oversee the establishment of

push–pull plots. They also train farmer teachers, many of

whom have now become experienced peer educators.

A hallmark of the successful spread of push–pull has

been icipe’s capacity to identify and work in harmony

with the many groups and organizations it meets in the

field. Exploiting synergies with other active research and

development organizations has created new channels

for spreading push–pull. Particularly important is icipe’s

Testing potential push–pull border crop grasses for drought tolerance at icipe’s Thomas Odihambo Campus, Mbita Point, Kenya.

Desmodium ramosissimum, shown here controlling striga in a plot of sorghum, is highly drought tolerant, but seeds are not yet commercially available.

Climate-smart push–pull 5

partnership with Heifer International, a non-governmental

organization (NGO) whose livestock-focused work

has proved to be a good fit with the technology, and

which is now the formal implementing partner for

climate-smart push–pull in Kenya and Tanzania.

By December 2015, the efforts of all partners meant that

about 47,000 smallholder farmers living in the drier parts of

Ethiopia, Kenya and Tanzania had taken up climate-smart

push–pull. According to Dr Charles Midega, Senior Scientist

in the push–pull programme, more than 100,000 farmers will

be planting climate-smart push–pull by the end of 2018.

Spreading benefits, increasing impactConventional push–pull, usually practiced with maize,

has already had significant impacts on food security,

human and animal health, soil fertility, income generation,

the empowerment of women and the conservation

of agro-biodiversity. Climate-smart push–pull is

spreading these benefits more widely, to additional

crops and regions with different agro-ecosystems.

These farmers are members of a Heifer International group in Kenya’s Rachuonyo district, and have planted a climate-smart push–pull plot with sorghum.

Eunice Omondi, who lives in Kenya’s Siaya district, added a climate-smart push–pull plot to her farm in 2012, and reports a

six-fold increase in her maize yield. As well as being a farmer, Eunice is also a community health worker. When she goes from

door to door in the villages, she explains the connection between diet and health and talks about push–pull as a way of getting

more food. As she says, “having enough food helps in healing”.

Dr Zeyaur Khan, Principal Scientist and Leader of

the push–pull programme at icipe, says “the new trap

plants and intercrops of climate-smart push–pull have

met farmers’ and scientists’ expectations. Yields of maize

and sorghum have increased significantly, sometimes as

much as five-fold when compared with control plots”.

The chart below presents yield data for 60 climate-

smart push–pull adopters, half growing maize and half

growing sorghum. Their push–pull yields are compared

with control plots of the same crops, grown without

companion or intercrop plants in western Kenya.

As well as increasing cereal yields, the new companion

plants have provided ample, good-quality livestock

fodder, producing enough to allow farmers to make hay

for the dry season. For most dairy livestock – cattle and

goats, improved and local breeds – a diet of push–pull

fodder results in more milk. In all, through the range of

benefits it provides, the system gives high economic

returns to the farmer and results in a range of positive

impacts on the livelihoods of farm households.

Yield(kg/ha)

Maize Sorghum

Adapted push–pull

Control ControlAdapted push–pull

4000

3000

2000

1000

0

Yield data for 60 climate-smart push–pull farmers

6 Climate-smart push–pull

Improving food security and healthOn-farm research confirms that, thanks to the rapid action

of the greenleaf desmodium in dealing with striga, yield

increases from climate-smart push–pull routinely result in

cereal harvests doubling over the course of a single season.

According to Jimmy Pittchar, Social Scientist in the

push–pull programme, “having enough grain to meet

household needs from one season to the next is the most

common local definition of food security in this region”.

Most push–pull farmers report that since adopting the

technology, they are now mainly food-secure. On-farm

results from three seasons have shown that the yield

gains that underpin this increased food security can be

maintained over time, thanks to the combined effect of

eliminating pests and weeds and improving soil fertility.

In many cases, push–pull farmers say that the diet and

therefore the health of their families have improved since

adopting the technology, particularly through drinking more

milk. Dietary diversity has also increased, with many farmers

reporting that they are in a better position to purchase

foods that they are not able to produce for themselves.

Providing nutritious fodderLivestock fulfil many purposes in the livelihood

systems of farming households. They provide milk,

meat, manure and draught power. Well-fed, healthy

animals play an important part in maintaining soil

fertility, providing dietary protein for farm households,

and generating income to pay for school fees.

Push–pull farmers use their fodder crops to feed

goats, sheep, cattle, pigs, poultry and even rabbits.

Many farmers report positive changes in the health and

productivity of their animals, particularly thanks to the

nutritional qualities of desmodium. Because it is rich in

protein, desmodium fodder frequently doubles or even

triples existing milk yields. Widespread reports from

adopting farmers suggest that the greenleaf desmodium

of climate-smart push–pull appears to have an even

more positive impact than silverleaf desmodium.

Generating incomeThere are a number of ways that push–pull generates cash

income, including the sale of cereals, milk and fodder.

Within the household, this increased income is most often

spent on school fees, but also used for improvements to

housing and investment in livelihood diversification.

But there are also many examples of income being

used to strengthen the social safety nets that protect

vulnerable community members, particularly those

affected by HIV/AIDS. These include the construction of

a primary school for orphans using profits from climate-

smart push–pull surplus, and the inclusion of push–pull in

the portfolios of income-generating activities conducted

by many self-help groups in Kenya and Tanzania.

Miriam Sureri in Kuria district, Kenya, planted her first push–pull plot in 2010, and more than doubled the original area with a climate-smart plot in 2012. Before adopting push–pull, she got two litres of milk a day from her local breed cows. With silverleaf desmodium and Napier grass, this went up to three litres, but with fodder from her climate-smart plot, her yield doubled to six. Two litres a day are kept for Miriam’s eight children, and the rest is sold to pay school fees.

Most of the members of the St. Mary’s Women’s Group in Kenya’s Suba district are widows. They planted a communal climate-smart push–pull plot in 2012, using the fodder to feed the dairy goats they received after working with the Italian NGO, European Committee for Agriculture and Training (CEFA). They aim to save enough money from milk sales to fence their push–pull plot and so protect it from free-grazing livestock.

Climate-smart push–pull 7

Evelyn Otunge’s husband died in 2003, and since then she has been raising their six children alone. She adopted push–pull in 2008 and planted a climate-smart plot with sorghum in 2012. “I used to work alone on a big portion of land, for very little produce,” she says. “But now I work a small area. It takes less labour, and produces more income.”

Promoting gender equityOnce established, push–pull reduces the drudgery

of digging and weeding, tasks most often performed

by women, freeing up their time and labour for

more productive tasks like selling milk or starting a

poultry enterprise. Diversified farm income means

there is more money available to buy medicines,

household goods and other essentials. Feeding

dairy cattle in stalls also frees women and children

from the task of herding cattle to graze.

Samuel Ong’ou had been cultivating a conventional push–pull plot for two years before he added a new climate-smart plot in 2012. He grows bananas, sweet potatoes and vegetables as well as maize and sorghum, and he feeds goats, cattle and poultry with push–pull fodder crops. In the long rainy season of 2013, the area of Rachuonyo district where Samuel lives experienced heavy rain at the onset followed by a long dry period, which finally ended with a hailstorm. Given these unfavourable climate events, Samuel was not expecting much cereal to be harvested this season. But he was nonetheless confident that the diverse enterprises on his farm, which all rely directly or indirectly on his push–pull fodder, were resilient enough to see his family through this lean season.

More stable and resilient agro-ecosystemsAs far as possible, climate-resilient agro-ecosystems

maintain the functions and services provided by natural

systems. This means integrating instead of segregating,

closing water and nutrient cycles, increasing biological

and genetic diversity, and regenerating instead of

degrading bio-resources. Push–pull technology contributes

to stable and climate-resilient agro-ecosystems by

providing farmers with a tool for on-farm diversification

that is in line with these underlying principles.

Farmers have for many years habitually diversified

the crops they plant as an insurance strategy against

climate uncertainty. Push–pull reinforces this strategy,

because it can be equally useful when applied to maize,

sorghum, millet and rice. Furthermore, having both

conventional and climate-smart variants widens the range

of planting material that farmers can use to tailor their

cereal cropping practices to local climatic conditions.

His Excellency Lodewijk Briet, Head of the European Union Delegation to Kenya, chats with Robert Atieng’a, a farmer teacher in Siaya district, during his visit in July 2013.

Looking aheadOne of push–pull’s strengths is the way the programme

has been managed as a learning process. Because farmer

participation is built in to research and dissemination,

contextual changes encountered in the field can be

communicated, discussed and responded to. Achieving

this level of reflexivity to contextual change is a vital aspect

of the climate-smart qualities of push–pull, and is thanks in

no small part to the flexible approaches of the many donor

organizations that have funded its development and spread.

Both the technology and its model for dissemination

represent a substantial resource for the future.

The development of climate-smart push–pull has

made it possible for the technology to travel to new areas

with lower rainfall, and to increase the potential number

of farmers who might find it a useful and profitable

addition to their livelihood strategies. In addition to the

work that has begun to extend climate-smart push–pull

Dr Zeyaur Khan, Principal Scientist and Leader of the push–pull programme at icipe, and Remjius Bwana, a farmer, inspect a climate-smart push–pull field planted with sorghum on Remjius’ farm in Kisumu West district, Kenya. A close relationship between farmers and scientists is at the heart of push–pull’s success, and is essential to its future adaptation and spread.

icipe

icipe—International Centre of Insect Physiology and EcologyP.O. Box 30772-00100

Nairobi, KenyaTel: +254 (20) 8632000

Fax: +254 (20) 8632001/8632002E-mail: icipe@icipe.org

in Ethiopia, Tanzania and Uganda, trials are being carried

out in Nigeria and the technology has been adapted for

use in South Africa. The profile of the technology is rising

steadily far beyond its homeland of Western Kenya.

The need for adaptive agricultural practices that

can cope with increasingly variable climatic conditions

and still produce food for people and livestock

has never been greater; neither has the need for

development pathways that respect ecological limits

and restore ecosystem health. Experiences with push–

pull offer important lessons about developing and

implementing the kind of climate-smart technologies

that are needed to meet these challenging goals.

AcknowledgementsThanks are due to the European Union for funding

the ADOPT Project (DCI-Food/2010/230224) for the

development and dissemination of climate-smart push–pull.